See division sign in Webster's New World College Dictionary
the sign (÷) used to indicate that the preceding number or quantity is to be divided by the following number or quantity (Ex.: 8÷4=2 or 2a÷a=2)
See division sign in American Heritage Dictionary 4
noun
The symbol (÷) placed between two quantities written on a single line to indicate the division of the first by the second.
The symbol (/) placed between two quantities written horizontally, as in 2/3 , or the symbol (-) placed between two quantities written vertically, as in 2/3 , to indicate a fraction.